public class VariableDemo02 {
    //主入口
    public static void main(String[] args) {
        //定义变量
        int x = 5;
        //打印变量
        System.out.println(x);

        //变量计算
        int y = 10;
        int z = 20;
        System.out.println(y + z);

        //变量修改
        x = 40;
        System.out.println(x);
    }
}
